Color bar codes are known in the art, though they are not prevalent. U.S. Pat. No. 5,426,289 to Kinoshita et al., U.S. Pat. No. 5,992,748 to Takahashi et al., U.S. Pat. No. 5,869,828 to Braginsky, U.S. Pat. No. 5,406,640 to Fitzpatrick, et al., U.S. Pat. No. 5,576,528 to Chew, et al., U.S. Pat. No. 4,044,227 to Hoim, et al., U.S. Pat. No. 4,488,679 to Bockhoh, et al., U.S. Pat. No. 4,939,674 to Price, et al. and U.S. Pat. No. 5,369,261 to Shamir teach different kinds of color bar codes.
Typically, a color bar code system creates color bar codes using N of colors For example, N might be 5. To make the code, each bar code color is associated with a numerical value and a color value. If there are N bar code colors, the bar code that uses that color scheme represents numbers in base N. One exemplary code (in the RGB color space) might be the following:
ColorNumerical ValueBlack0Blue1Green2Red3Yellow4
In this example, there are five bar code colors and thus, the code is in base 5. For example, a color bar code of [black, blue, green, yellow] represents the number 0124 in base 5 which translates to the base 10 number of 0*125+1*25+2*5+4=39.
When printing a particular bar code, the color values of the various regions in the bar code are sent to the printer which, in turn, prints the color bar code. After printing, the color bar code is placed onto an item to be labeled. A color bar code reader is typically a color camera that includes an image sensor, such as a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor) camera, and a relevant optical system. The reader reads the bar code and the bar code system identifies the item from the bar code. One exemplary color bar code system is discussed in PCT Publication WO 00/04711 to Shniberg et al., assigned to the common assignee of the present invention, which disclosure is incorporated herein by reference.
Unfortunately, every printer has a limited set of colors that it can print. This set of colors usually does not cover the entire color space. Moreover, the set of all possible colors is perceived, under any illumination, as a new and different set of colors in the color space.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.